From 48d4180939e12c4bd2846f984436d895bb9699ed Mon Sep 17 00:00:00 2001

From: Vishal Verma <vishal.l.verma@intel.com>

Date: Wed, 16 Nov 2022 16:37:37 -0700

Subject: [PATCH] ACPI: HMAT: Fix initiator registration for single-initiator systems

Git-commit: 48d4180939e12c4bd2846f984436d895bb9699ed

Patch-mainline: v6.1-rc8

References: git-fixes

In a system with a single initiator node, and one or more memory-only

'target' nodes, the memory-only node(s) would fail to register their

initiator node correctly. i.e. in sysfs:

  # ls /sys/devices/system/node/node0/access0/targets/

  node0

Where as the correct behavior should be:

  # ls /sys/devices/system/node/node0/access0/targets/

  node0 node1

This happened because hmat_register_target_initiators() uses list_sort()

to sort the initiator list, but the sort comparision function

(initiator_cmp()) is overloaded to also set the node mask's bits.

In a system with a single initiator, the list is singular, and list_sort

elides the comparision helper call. Thus the node mask never gets set,

and the subsequent search for the best initiator comes up empty.

Add a new helper to consume the sorted initiator list, and generate the

nodemask, decoupling it from the overloaded initiator_cmp() comparision

callback. This prevents the singular list corner case naturally, and

makes the code easier to follow as well.

Cc: <stable@vger.kernel.org>

Cc: Rafael J. Wysocki <rafael@kernel.org>

Cc: Liu Shixin <liushixin2@huawei.com>

Cc: Dan Williams <dan.j.williams@intel.com>

Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

Reported-by: Chris Piper <chris.d.piper@intel.com>

Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

Link: https://lore.kernel.org/r/20221116-acpi_hmat_fix-v2-2-3712569be691@intel.com

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Acked-by: Takashi Iwai <tiwai@suse.de>

---

 drivers/acpi/numa/hmat.c | 26 ++++++++++++++++++++------

 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/drivers/acpi/numa/hmat.c b/drivers/acpi/numa/hmat.c

index 144a84f429ed..6cceca64a6bc 100644

--- a/drivers/acpi/numa/hmat.c

+++ b/drivers/acpi/numa/hmat.c

@@ -562,17 +562,26 @@ static int initiator_cmp(void *priv, const struct list_head *a,

 {

 	struct memory_initiator *ia;

 	struct memory_initiator *ib;

-	unsigned long *p_nodes = priv;

 	ia = list_entry(a, struct memory_initiator, node);

 	ib = list_entry(b, struct memory_initiator, node);

-	set_bit(ia->processor_pxm, p_nodes);

-	set_bit(ib->processor_pxm, p_nodes);

-

 	return ia->processor_pxm - ib->processor_pxm;

 }

+static int initiators_to_nodemask(unsigned long *p_nodes)

+{

+	struct memory_initiator *initiator;

+

+	if (list_empty(&initiators))

+		return -ENXIO;

+

+	list_for_each_entry(initiator, &initiators, node)

+		set_bit(initiator->processor_pxm, p_nodes);

+

+	return 0;

+}

+

 static void hmat_register_target_initiators(struct memory_target *target)

 {

 	static DECLARE_BITMAP(p_nodes, MAX_NUMNODES);

@@ -609,7 +618,10 @@ static void hmat_register_target_initiators(struct memory_target *target)

 	 * initiators.

 	 */

 	bitmap_zero(p_nodes, MAX_NUMNODES);

-	list_sort(p_nodes, &initiators, initiator_cmp);

+	list_sort(NULL, &initiators, initiator_cmp);

+	if (initiators_to_nodemask(p_nodes) < 0)

+		return;

+

 	if (!access0done) {

 		for (i = WRITE_LATENCY; i <= READ_BANDWIDTH; i++) {

 			loc = localities_types[i];

@@ -643,7 +655,9 @@ static void hmat_register_target_initiators(struct memory_target *target)

 	/* Access 1 ignores Generic Initiators */

 	bitmap_zero(p_nodes, MAX_NUMNODES);

-	list_sort(p_nodes, &initiators, initiator_cmp);

+	if (initiators_to_nodemask(p_nodes) < 0)

+		return;

+

 	for (i = WRITE_LATENCY; i <= READ_BANDWIDTH; i++) {

 		loc = localities_types[i];

 		if (!loc)

-- 

2.35.3